Scarlet fever has reached its highest level in 50 years, with more than 19,000 cases reported in England in 2016.
After decades of decline in incidence of scarlet fever, a ‘dramatic’ increase began in 2014.
Incidence of scarlet fever tripled between 2013 and 2014, rising from 4,700 cases to 15,637 cases, with the majority of incidents occurring in England. In 2016, there were 19,206 reported cases, the highest level since 1967.
Investigators examined the Public Health England records from 1911 to 2016 in England and Wales in an attempt to identify the reason for the sudden escalation.
‘Reasons for this escalation are unclear and identifying these remains a public health priority,’ the study published in The Lancet said.
It was found that between 2013 and 2016, hospital admissions in England for scarlet fever increased by 97%.
Data for 2017 suggests the rate of outbreaks may be decreasing, but the study suggests that it is too early to tell if this trend will continue.
Molecular genetic testing has ruled out a newly emerged strain of the infection, nor was there any suggestion that the disease had become resistant to the penicillin normally used to treat it.
Several countries in East Asia have also reported an escalation over the past five years, including Vietnam, China, South Korea, and Hong Kong.
Typically, natural cyclical patterns of scarlet fever incidence occur every four to six years, the researchers said, and therefore the dip in 2017 suggests the cycle may have peaked in 2016.
In England and Wales, all cases of scarlet fever must be reported by healthcare professionals to the local health authority.
In Scotland, scarlet fever is more difficult to track because doctors are no longer obliged to notify their local health authority of any outbreak.
‘We use upper respiratory tract group A streptococcal laboratory detections, the bacteria that causes scarlet fever, as an indicator of the level of scarlet fever in the community,’ an NHS Scotland spokesman said.
‘These bacteria are currently slightly higher than expected levels for this time of year in Scotland.’